body {
    text-align: center;
}

#main {
    text-align: left;
    width: 1000px;
    margin: 0 auto;
}

table tr td>div {
    width: 480px;
    height: 300px;
    margin: 10px;
}

table tr td>div>div.panel-body {
    margin-left: 5px;
    margin-right: 5px;
}